Metod of obtaining fatty alcohols from their esters



AMaly 2, 1950 s.' STEINBERGER- METHOD 0F OBTAINING FATTY ALcoHoLs FROMTHEIR ESTERS Filed June 1o, 1948.

2 Sheets-Sheet 2 TTORNEYS Patented May 2, 1950 METHOD OF CBTAINING FATTYALCOHOLS FROM THEIR ESTERS Samuel Steinberger, Brooklyn, N. Y., assignorto The Richards Chemical Works, Jersey City, N. J., a corporation of NewJersey Application .lune 10, 1948, Serial No. 32,102

12 Claims.

This invention relates to an improved method for obtaining higher fattyalcohols from their esters as found in sperm oil, spermaceti, waxes, andother esters of alcohols containing S to carbon atoms or more andincluding both natural esters (waxes, etc) and synthetic esters of suchhigh boiling fatty alcohols with fatty acids.

Heretofore the principal method for recovering such higher alcohols fromtheir esters has consisted of saponifying the esters at necessarilyelevated temperatures, with essentially anhydrous, strong alkalies suchas caustic soda, caustic potash, or mixtures thereof or calciumhydroxide, followed by distillation with dry steam under reducedpressures and at relatively high temperatures. The still bottomsresulting from such distillation are usually of high softening.

point and high Viscosity and must be removed from the still at anelevated temperature.

The present invention provides an improved process for obtaining higherfatty alcohols from their esters in which the successive operations ofsaponiiication, distillation and removal of residues are facilitated bythe employment of a high boiling, water-miscible solvent which is asolvent for the fatty alcohols and the soap formed during thesaponication, for example, an ether-alcohol such as triethylene glycoland the like.

The improved process in which such high boiling, water-miscible solventsare used has very practical advantages. The employment of such solventslowers the temperature required for saponification and permitssaponification to be effected within a reasonably short period of timeand lowers the softening point of the residual soap mass resulting fromthe distillation of the fatty alcohols therefrom. The use of such highboiling solvents also promotes the distillation of the fatty alcoholsfrom the saponied esters and gives a distillate containing both thefatty alcohols and solvent. The water-miscible properties of the highboiling solvent enables strong aqueous caustic alkali solutions to beemployed for the saponification, as well as solid and essentiallyanhydrous alkalies. The utilization of such watermiscible solvents alsopermits alcohols to be separated from admixed high boiling solvent byadding water to form an aqueous-solvent layer in which the fattyalcohols are insoluble. The presence of the high boiling water-misciblesolvents is also advantageous in the saponication residue, which can bediluted with water to form an aqueous solution of soap and solvent andthen acidined to set free the fatty acid from the soap and form anaqueous solvent solution which also contains salt.

. The present invention includes improvements in the saponificationoperation, in the distillation operation, in the residual soap treatingoperation, in .the separation of distilled fatty alcohol from highboiling solvent, and in cyclic operations in which the high boiling,water-miscible solvent is separated from its aqueous solution for reusein the process.

The high boiling solvents used have boiling points or have a boilingpoint range similar to that of the higher fatty alcohols, for example, aboiling point range under ordinary atmospheric pressure of around 200 to350 C. The high boiling solvents may have a boiling point somewhathigher than that of the fatty alcohol to be distilled or somewhat lowerthan that of the fatty alcohol. And where the ester saponied gives highboiling alcohols of different boiling points the solvent may have aboiling point higher or lower or between those of thealcohols. The highboiling solvents used have such a high boiling point that thedistillation of the higher fatty alcohols is at a temperature such thatthe saponiiication mixture in the still is anhydrous, and thedistillation results in the production of an anhydrous soap residuediluted with the high boiling solvent, while the mixed distillate ofhigher fatty alcohol and solvent is also anhydrous, except for thepresence of some water which may be present during the saponication andwhich may be removed during the early portion of the distillation.

The solvents used are not only high boiling, but are alsowater-miscible. Among such high boiling water-miscible solvents areincluded various members of the group of ether-alcohols such aspolyalkylene glycols and alkyl ethers thereof as well as high boilingwater soluble polyamines such as polyalkylene polyamines, andalkylolamines such as triethanolamine. Among such high boiling solventsmay be mentioned ethylene glycol, diethylene glycol, triethylene glycol,tetraethylene glycol, dipropylene glycol, tripropylene glycol, butyleneglycol, ethoxy triglycol, dimethoxytetraglycol, triethylene tetramine,tetraethylenepentamine, triethanolamine, amino ethyl ethanolamine,methyl diethanolamine, etc.

Where the fatty alcohols have a boiling point range around 200, the highboiling water-miscible solvents advantageously have a similar boilingpoint. With esters such as those of sperm oil and spermaceti, thealcohols from which have higher boiling points, higher boiling solventsare advantageously used.

The solvents in some cases permit distillation of the fatty alcohol totake place at a temperature lower than that at which either the alcoholor the solvent alone will distill, apparently forming constant boilingmixtures. Even where such constant boiling mixtures are not formed thealcohol and solvent will be distilled together and the distillation ofthe solvent will promote or facilitate the distillation of the alcohol.

The solvents used promote the saponliication.

An advantageous method of carrying out the process is by using strongaqueous solutionsl of sodium or potassium hydroxide instead of the solid'and essentiallyh anhydrous alkales. With water vmiscible high'boilingsolvents the saponif`ication can be carried 'out by employing suchstrong, aqueous caustic solutions without appreciablyV affecting thesaponication rate or the quality of the"saponi'icatio'n, while themixing and handling of the reaction mixture is facilit'ated.

The saponication step and the subsequent distillation step 'of theprocess can be carried out in the same vessel which will serve iirst asreactionvessel at a lower temperature and later as la still vat a highertemperature. processing time may be reduced in this case by beginningthe distillation before the saponincation isbompleted, with the twoprocesses pro ceedin'g simultaneously. The apparatus or vese sels orVstills employed will be provided with suit-` able heating means andwith stirrers or agitators. Where saponiiication' is carried out in onevessel and distillation in another, the saponiiication may be completedbefore the distillation begins or the incompletely saponied charge maybe transferred to the still and the saponication completed during theearly period of distillation.

The distillation of the high'boiling fatty alcohols is carried out atpressuresbelow atmospheric in order to take advantage of. the lowtemperatures at which the charge maybe maintained in the rluid stateaswell as tov insure greater heat economy. Other things being equal,Ythe. degree of vacuum required is` preferablythat which will yield ahigh ratio of fatty alcohol to solvent in the distillate.

In general the amount ofasolvent present in the sapoiiication step maybekept to a minimum, with the use of. sufcient solvent to give a thinlyiuid mixture for saponiflcation, but without undue dilution of thereaction mixture with. sol.- vent. During. the course of thedistillation, however, more solvent isy advantageously added asrequiredto make up for. that which is distilled with the fatty alcoholand to insure thatall of the fatty alcohol is distilled from the charge.Practically quantitative yields` of alcohol could be obtained. Duringthe early or main portion of the distillation a high ratio of fattyalcohol to solvent is distilled. After most of the fatty alcohol hasbeen distilled, during the last portiongof the distillation, theI'distillate is largely solvent; and this pOrton of the distillate isadvantageously set aside and reused in a succeedingbatch. Thedistillation is remarkable for its almost complete freedom from foaminguntil the still bottoms contain. a 4low concentrationof solvent. "lhe"zdistillationl residue can be freed from most of its,` solvent butysuiiicient solvent should be. left to insure that the residue is stilliiuidwhencooled:.IY The distillation residue The total is an anhydroussoap diluted with anhydrous solvent.

After the distillation, the residue in the still is cooled to a pointwhere it is still fluid, which is the case at moderate temperatures, andthe process is in this respect distinguished from processes carried outin the" absence of a solvent where the residue is highly viscous even at200 C. or higher in the case of s permacetl. After cooling the fluid,anhydrous residue is added to aqueous acid, or is added to water withsubsequent addition of acid, to set free the fatty acids which separateas a layer on top of the aqueous solvent layer. The water-misciblesolvent readily mixes with the added water. Any solvent separating withthe fatty acids is readily washed out to give a substantiallysolvent-free fatty acid layer. The aqueous solvent` mixture containingsalt from the acidification' of the soap is advantageously treatedthereafter' to recover the solvent for reuse.'

The distillate is advantageously collected in two separate parts, therst and main part containing most of the fatty alcohol mixed withanhydrous solvent; and the latter part being mainly solvent with a smallamount of fatty alcohol. This second amount of anhydrous solvent with asmall amount of fatty alcohol is advantageously returned to the processand used as a solvent in treating a further. batch of ester. The mainportion of the, distillate is advantageously treated by adding waterwhich extracts the solvent and separates the insoluble fatty alcohol,giving a fatty alcohol layer and an aqueous solvent layer. The fattyalcohol fraction, after washing with fresh Water, is of aV high grade.The aqueous sc ,Jlvf-:nt` mixture isthen distilled to remove the watervand give anhydrous solvent for return to the process.

Ehe separation ofthe solvent andl fatty alcohol can be carried out bythe use ofv organic materials such as ligroin, etc. which exert aselective solvent action and extract the alcohol from the` high boilingsolvent. But for practical operation, the use of water to separate thewatermisciblehigh boiling solvent from the high boiling fatty alcoholisa more advantageous method.

The nature of the process will be further described connection with theaccompanying drawings which illustrate, in a somewhat conventional anddiagrammatic manner, in Fig. l, an arrangement of; apparatus andprocessing steps, and in Eig. 2'-, a flow sheet, but it will beUBFeFSPQQd; that; the iliverltiorl.V is. not limited thereto.

Referring tov the4 diagrammatic arrangement shown in Eig. 1, acauvstic;liquor. supply tank is conventionallyshown at l, supply, tanks for esterat2` and 3, for sperrngoiland.spermaceti, respectively, as. theesters'.to; betreatecl and a solvent supply is, indicatedconventionally at d.These supply, tanks, are connected through pipe connectionshavingscontrol-valves therein and meters 5, thereinto.the,sapQniiier-.-and still E, having stirrer. 'i thereinandprovidedwith heating `means (not, shown), The. arrangement vis, suchthat -a suitable. charge4 of esterasuch as sperm oil or spermaceti withanfappropriate charge-of caustic liq'uorand solvent caribesuppliedinitially to saponiiier, fon theA saponicationstep of theprocess; and additional solvent can: be supplied as` required, duringLthe.V subsequentdistillation step.

The Adistillate fronihe stillA 6: is condensed in the. 001.1@ensei,-gfand; collected yin thezrecever.. 9

which is connected through the line I with a vacuum pump (not shown) bywhich a high vacuum can be maintained on the still during distillation.From the receiver 9 the main portion of distillate containing most ofthe high boiling fatty alcohol is collected in the concentrateddistillate storage receptacle II, while the latter part of thedistillate containing mainly solvent and with a small amount of fattyalcohol is collected in the dilute distillate storage tank I2 andreturned through the line I3 to be added to the solvent in the tank 4,so that this solvent can be used over again in a subsequent charge andits fatty alcohol content subsequently recovered.

The concentrated distillate in the form of an anhydrous mixture of highboiling solvent and high boiling fatty alcoho1 passes from the tank IIthrough the line I4 to the proportioning pump I5 and then through theline I6 to the bottom of the tank Il, where dilution takes place withseparation of alcohol and a concentrated aqueous solvent layer. Thealcohol passes through line 24 to the bottom of a second separating tankI9 where the alcohol is further washed with water to remove solvent fromit and the resulting crude fatty alcohols pass through the line to thestorage tank 2 I.

Water is supplied through the proportioning pump 22 and passes throughthe line 23 to the top of the tower I9 Where the fresh water serves towash the fatty alcohol passing upwardly therethrough, to removewater-miscible solvent from it. The resulting dilute aqueous solventsolution passes through the line I8 to the top of the tower I1 where itserves to effect the preliminary separation of the solvent-alcoholmixture into an upper alcohol layer and a lower layer of concentratedaqueous solvent. The concentrated aqueous solvent is drawn olf throughthe line 25 to the dewatering column or still 26, where the mixture isheated and water distilled through the line 21 and from which theresulting anhydrous solvent is returned through the line 28 to thesolvent storage tank 4.

After the distillation of the flatty alcohol from the still iscompleted, and after part of the remaining solvent has been removed fromthe still, the residue, made up of the anhydrous soap and sufficientsolvent to give a liquid mixture, is discharged through the line 30 tothe acidifying vat 3| where it is treated with acidified water to setfree the fatty I'acids from the soap, and to form an aqueous solventlayer containing the salt formed. r["he crude fatty acids are drawn offthrough the line 32 to the crude fatty acid storage tank 33. The brinecontaining the salt and the organic solvent in aqueous solution is drawnoff through the line 34 and is also subjected to concentration todistill the water from it and to separate the salt from it and to givesolvent which can also be returned for further use in the process.

In the alpparatusand diagrammatic arrangement of process stepsillustrated and above described, and in the flow sheet of Fig. 2, thesolvent and caustic will be charged to the agitated salponilcationkettle through meters o-r weighing tanks and heated and the ester fromthe storage tank added and the saponication then conducted more or lessto completion. In the arrangement shown in Fig. l the mass is distilledin the same vessel, although it could I,be transferred to a separatestill as shownV in Fig. 2. or stored for treatment in a continuous 6distillation system. The distillate is diverted either in theconcentrated storage tank for further treatment to separate the fattyalcohol from the solvent and to recover the solvent for reuse; or, inthe later stages of distillation the dis-- tillate may be diverted intothe tailings or dilute distillate storage receiver from which solventfor the next sraponication batch may be drawn, or returned to thesaponier as shown in Fig. 2.

"In the course of the distillation additional solvent will be drawn fromthe storage tank as required to replace the solvent driven olf with thefatty alcohol and to insure that the charge in the still is freed fromall of the fatty alcohol. The residue from the still may then be cooledas desired and dropped into the laciclied water to liberate the fattyacids from the soap and to give a crude fatty acid as one of theproducts of the process. 'Ilhe lye or brine from which the fatty acidsare separated and which contain salts, water and solvent may beconcentrated to remove water and precipitate the salts and to recoverthe solvent for reuse.

'Ihe concentrated distillate from the still may be treated with watereither batchwise or continuoirsly to separate fatty alcohols from thesolvent. In the arrangement shown in Fig. 1 the distillate is passedsuccessively through the countercurrent extraction towers I'I and lI9against water with regulation of the amount of water and distillate bythe proportioning pump. The washed, crude alcohol goes to the storagetank from which it may be removed for drying, fractionation or immediateuse. The diluted solvent is then passed through the concentrating columnwhere it is freed from water and the solvent recovered and returned tothe process.

The cyclic nature of the Iprocess and the inter-- relation of thevarious steps when carried out; in a cyclic manner is illustrated in thedrawings.` It will be seen that the same high boiling, watermisciblesolvent is recovered and used in a cyclicv manner. From the drawings,and from the foregoing description, it will be seen that the highboiling solvent is added :and is :present during saponiication topromote the saponification; that it is also present and is used duringthe distillation to promote the distill-ation; and that advantage istaken of the water-miscible properties of the solvent to facilitateseparation of the fatty alcohols therefrom and also to facilitate theacidification of the soap and the recovery of fatty acids therefrom;while the solvent, separated as an aqueous solution, is freed from waterand returned to the process in a cyclic manner.

The invention will be further illustrated by the following specificexamples lhut is not limited thereto.

Example 1.-A mixture of 400 parts of triethylene glycol and 40 lparts of48 Be. NaOH (assaying 47.1% NaOH and 0.8% NaZCOa) was heated to C.,whereupon 200 parts of spermaceti was added gradually. The mixture wasthen heated with agitation to 95 C. for one and one-half hours.Titration of an aliquot at this point indicated that the saponificationywas essentially complete.

202 parts of the mixture containing 28.4 parts of fatty alcohols wastransferred to a distilling vessel and distilledy lat a pressure of 8-12mm. absolute. Additional glycol was added at intervals. A first cutdistilling between 146 and 160, and amounting to 122 parts, contained19.9 parts or 70% of the theoretical. Further cuts, total.

7 ling 188 parts, brought the recovered alcohol to 28.4 parts, orapproximately 100%.

To the above distillate, water was added suficient to bring the glycolconcentration to a 70 aqueous solution (70% solvent and 30% water); thealcohols separated almost quantitatively from the solution, andcontained-only a small amount of glycol and Water. This wasy removed by'a second wash.

Example 2.-To a mixture of 330 parts of tetraethylene glycol and 54parts of 40% aqueous NaOH at 70 C., 210 parts of sperm oil was addedgradually, and the mixture was heated to 90 C; for about two hours.Saponification was essentially complete.

To 559 parts of this product corresponding to 196 parts of sperm oil,was added 100 parts more tetraethylene glycol, and the mixture was dis-ytilled at ia pressure of 16i2 mm., between 180 and 205 C. 95 parts ofdistillate contained 37 parts of fatty material. As the distillationproceeded, more of the glycol was introduced; sucmaterial, totaling40.3% of the sperm oil taken.

Addition of water to the distillate caused a separation into two layers,the upper of which contained practically all of the fatty alcohols.

Example 3.-210 parts of sperm oil, 400 parts of triethanolarnine'and 54parts of 40% NaOH were heated for one and one-half hours at 90-'100 C.Distilledat -16 mm. between 18S-207 C. a main fraction containing 42% offatty alcohols, amounting to 37.5% or the sperm oil taken, was removed;further distillation yielded a less concentrated cut, bringing the totalyield to 41.8% on the weight of the sperm oil.

Addition of water to the distillate caused a separation into two layers,the upper of which contained practically all of the fatty alcohols.

The above examples illustrate the saponiiication and distillation stepsof the process and the .separation of the fatty alcohols from the highboiling wateremiscible solvent. The recovery of the solvent for reuseand the acidification of the .soap to recover fatty acids are notincluded in the :above examples.

it will thus be seen that the present invention 'provides an improvedmethod for recovering high boiling. fatty alcohols from their esters inwhich 'high boiling water-miscible solvents are used to promote thesaponii-lcation and subsequent dise tillation; and that such solventsare advantage ously used in a cyclic man-ner. It will further be seenthat the use of-such high boiling watermiscible solvents has manyadvantages in profmoting the saponication and distillation as well asthe subsequent treatment of distilled residue and the recovery of thedistillate, Iadvantage bee ing taken of both the high boiling propertiesof the solvents during the distillation and of the water-miscibleproperties of the solvents to promote separation ci the reactionproducts.

I claim: v

1. The method of recovering high boiling fatty alcohols containing 8 toY2G carbon atoms or more from their esters which comprises saponifyingsuch esters with an alkaline agent inthe pres'- ence of a water-misciblesolvent which is al sole vent for the fatty alcohols' an'd soap' formedby the saponiication and which has a boiling point withinV the rangefrom about 200' to about 350 C.,

and then distilling the mixture to obtain a codistillate containingsuchl solvent and the fatty alcohols.

2f. The improvement in the methodof recover-i ing of fatty alcoholscontaining 8 to 20 carbon atomsfrom their esters by saponifying suchesters with an alkaline agent and then distilling the alcohol from thes-aponilcation mixture, which comprises promoting the distillation ofthe fatty alcohol by carrying out such distillation of the saponicationmixture with a water-miscible solvent which is a solvent for the fattyalcohols and soap formed by the saponication and which has a boilingpoint within the range from about 200 to about 350 C., to obtain aco^distillate containing such solvent and the fatty alcohols.

3. The process according to claim 1 in which the co-distillate ofwater-miscible solvent and fatty alcohols is treated with Waterv toseparate the fatty alcohols and form an aqueous solvent mixture and inwhich the solvent is recovered from such aqueous mixture by distillationfor further use in the process.

4. The process according to claim 1 in which the residue from thedistillation, in the form of an anhydrous mixture of soap and solvent,is treated with acidined water to set free the fatty acids and form anaqueous-solvent-salt mixture, followed by separation ofA the solventfrom the water and salt and return of the solvent to the process.

5. The process according to claim 1 in which the cc-distillate ofsolvent and fatty alcohols is obtained in the form of a C13-distillatewith a'high content ci" fatty alcohols and a nal distillate of solventwith a small amount of fatty'alcohols; with return of theseconddistillate for use as a solvent in the further carrying out of thesaponication step of the process.

The process according to claim 1 in Which the co-distillateof solventand fatty alcohol is treated with Water to separate the fatty alcoholand form an aqueous-solvent mixture by passing the distillate throughsuccessive treatments of counter-now with waterfto form a concentratedaqueous solution of the solvent. and to wash the alcohol free fromsolvent, followed by distillation of the aqueous solvent and return ofthe resultingv anhydrous solvent to the process.

7. The process according to claim l'in which the water-miscible solventis a polyalkylene glycol solvent.-V

8. The process` according to claim 1 in which the water-miscible solventis a polyalkylene glycol ether solvent.

Y 9. Thev process according to claim 1 in which the water-misciblesolvent is triethylene glycol.

10. The process according to claim 1 in which the water-miscible solventis a polyamine.

11. The process according to claim 1 in which the water-misci'elesolvent is an alkylolamine.

12. The process according to claim- 1 in which additional solvent isadmixed with the mixture being distilled in order to maintain suchmixture in a iiuid condition without undue dilution of said mixture. v

SAMUEL STEINBERGER.

REFERN'CES CITED VThe following references are oi record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date I 1,814,654 Youtz July 14, 19311,967,319 Moore et al July 24', 1934 2,021,926 'sexton -n n Nov. 26,1935 2,245,538 Thurman che- June-10, 1941

1. THE METHOD OF RECOVERING HIGH BOILING FATTY ALCOHOLS CONTAINING 8 TO20 CARBON ATOMS OR MORE FROM THEIR ESTERS WHICH COMPRISES SAPONIFYINGSUCH ESTERS WITH AN ALKALINE AGENT IN THE PRESENCE OF WATER-MISCIBLESOLVENT WHICH IS A SOLVENT FOR THE FATTY ALCOHOLS AND SOAP FORMED BY THESAPONIFICATION AND WHICH HAS A BOILING POINT WITHIN THE RANGE FROM ABOUT200 TO ABOUT 350*C., AND THEN DISTILLING THE MIXTURE TO OBTAIN ACODISTILLATE CONTAINING SUCH SOLVENT AND THE FATTY ALCOHOLS.